DE 39 21 242 C1 (which is the priority document for U.S. Pat. No. 4,997,407) describes a centered double universal joint with two outer joint yokes articulatably connected by a cross member to two inner joint yokes to form part of a housing. An annular recess is formed in the housing. A guiding disc is radially adjustably supported in the housing. Floating annular guiding plates sandwich the guiding disk. The guiding disc includes a centrally arranged guiding projection. The projection projects from both sides of the guiding disc. The outer joint yokes, whose yoke arms are connected to one another by a bridge, each include a journal projection. The journal projection includes a spherical face and is pivotably supported in a bore of the central guiding projection of the guiding disc. The cross members each include lubricating channels which are used to lubricate rolling contact bearings. The rolling contact bearings support the cross member in the yoke arms. The lubricating channels are each connected to lubricant guiding means in the journal projections. The channels open into the bore of the central guiding projection of the guiding disc. At least one radially extending lubricant channel is provided in the guiding disc. The channel connects the bore in the central guiding projection to the annular recess. It is thus possible to convey lubricant from a lubricating nipple, provided at the cross member, into the annular recess. The disadvantage, however, is that at high rotational speeds of the double universal joint, the lubricant is thrown radially outwardly as a result of the centrifugal forces. This has an adverse effect on the lubrication of the guiding disc and the guiding plates.
DE 28 02 572 C2 (which is the priority document for U.S. Pat. No. 4,257,243) discloses a centered double universal joint wherein a guiding disc, articulatably connected via centering projections to outer joint yokes, is radially adjustably guided in an annular recess. The housing includes a lubricating nipple which is directly connected to the annular recess by a lubricant channel. Thus, the rolling contact bearings of the cross members and the annular recesses are lubricated independently of one another. Accordingly, the lubricant is pressed radially outwardly by the centrifugal forces.